Vitamin K

Vitamin K is a fat-soluble vitamin. Fat-soluble vitamins are stored in the body in the liver and fatty tissues. Unlike the other fat-soluble vitamins, the body actually stores very little vitamin K. This makes regular dietary intake important. Bacteria in the large intestines help by making a range of vitamin K forms called menaquinones. Vitamin K is also produced by plants (phylloquinone) and is primarily found in green vegetables, brussels sprouts, cabbage, and plant oils. The man-made vitamin K found in supplements is called menadione.

Functions

Vitamin K’s functions include:

Playing an essential role in the blood-clotting process by making the proteins that stop bleeding

Helping your body make other proteins essential for blood, bones, and kidneys

Recommended Intake:

Age Group
(in years)
Adequate Intake (AI)
(in micrograms)

FemalesMales

1-33030

4-85555

9-136060

14-187575

14-18 Pregnancyn/a

14-18 Lactation

19+90120

19+ Pregnancyn/a

19+ Lactation

Vitamin K Deficiency

If you do not get enough vitamin K, your blood will not clot normally. Among healthy people, a deficiency is rare. Symptoms of vitamin K deficiency include:

Easy bruising and bleeding—nosebleeds, bleeding gums, blood in the urine, blood in the stool, or extremely heavy menstrual bleeding

Bleeding in the skull in infants

Vitamin K Toxicity

As a fat-soluble vitamin, vitamin K is stored in the body in small amounts. No tolerable upper intake level (UL)—that is, the highest amount healthy people can consume without endangering their health—has been established for vitamin K. However, excess amounts can cause the breakdown of red blood cells and liver damage.
To be safe, you should follow the intake guidelines based on your age and gender

Major Food Sources

Foods that are high in vitamin K include:

Broccoli

Brussels sprouts

Cabbage

Kale

Collard greens

Bib lettuce

Spinach

Green pepper

Canola and soybean oils

Rhubarb

Mangos

Health Implications

If You Take a Blood-thinning Drug

If you take a blood-thinning drug (anticoagulant), try to consume the recommended intake of vitamin K. Avoid exceeding this. Taking a vitamin K supplement can change the effectiveness of the drug. Talk to your doctor about your how much vitamin K is safe for you.

If You Take Antibiotics

In addition to killing harmful bacteria, antibiotics also destroy the healthful bacteria that live in the intestines and produce vitamin K. You may need to add more foods rich in vitamin K to your diet. Ask your doctor.

If You Have Liver Disease

The liver plays an important role in metabolism and storage of vitamin K. If you have severe liver disease, you may need to take a vitamin K supplement to avoid complications.

If You Have a Newborn Baby

Because vitamin K deficiency can be life-threatening in infants, the American Academy of Pediatrics recommends that all newborns receive an injection of phylloquinone, a plant-based vitamin K. This is the standard of care in most hospitals.

Tips For Increasing Your Vitamin K Intake

Slice an avocado. Add a little balsamic vinegar and pepper, and scoop out for a snack. Or, mash the avocado and mix with chopped tomatoes and red onions for a refreshing salsa.

Pack a kiwi and spoon in your lunch for an afternoon snack. The insides of the kiwi can be scooped out and eaten from this natural and easy container.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.